Fisher's
From Surface To Objects: Computer Vision and
Three Dimensional Scene Analysis,
1989

Jain and Dubes'
Algorithms for Clustering Data, 1988.

When you can measure what you are speaking about,
and express it in numbers,
you know something about it;
but when you cannot measure it,
when you cannot express it in numbers,
your knowledge of it is of a meager and unsatisfactory kind;
it may be the beginning of knowledge,
but you have scarcely, in your thoughts,
advanced it to the stage of science.

— Sir William Thompson, Lord Kelvin (1824-1907)

It is a capital mistake to theorize before one has data.
Insensibly one begins to twist facts to suit theories,
instead of theories to suit facts.